Thumbnail Image

Theses

Browse

19881
Reset filters
Subject: Aquaculture × Author: KAU × Author: Navas, K A × End date: 1989 × Start date: 1988 × Type: Thesis × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Effect of low salinities on the growth and survival of Penaeus mondon Fabricus
    (Department of Aquaculture, College of Fisheries, Panangad, 1988) Navas, K A; KAU; Sebastian, M J
    Growth and survival of P.monodon are influenced by a number of ecological factors (Chakraborti et al. 1986) salinity, being one of the most important of them. Knowledge on the tolerance of this species to low salinity conditions has great implications in its culture especially in extending its culture to low saline fields. In the present study, the postlarvae were subjected to wide fluctuations in salinity ranging from 1 to 20ppt. The influence of gradual acclimation in improving ranges of tolerance of postlarvae was studied. The lowest lethal salinity (LC 50) was determined by step-wise reduction of salinity. Salinity in which more than 50% mortality occurred at the end of 120h was considered lethal. Growth of juvenile in different test salinities ranging from 1 to 20 ppt for a period of 56 days was undertaken. Preliminary tolerance studies indicated that fluctuations in salinity ranging from 4 to 20ppt did not influence the survival of postlarvae significantly (P>0.05). Gradual acclimation extended the range of tolerance. A probit regression line for the relation between the logarithmic salinity level (dose =X) and mortality (Probit response =Y) was found to be Y=5.982023 + 1.332194X. The lowest lethal salinity (LC 50) was 0.5479 ppt with its upper and lower limits being 0.377 and 0.790 ppt respectively. Post larvae exhibited abnormal behaviour and higher rate of cannibalism at suboptimal salinities. Low salinities had a highly significant influence on the growth of juvenile (P<0.001). However, mean values of growth rate between 4 and 15 ppt did not differ significantly (P>0.05) from the control (19.5 + 0.5 ppt). Shrimps reared in different test salinities were subjected to sensory evaluation. Flavour of cooked meat of shrimps differed significantly with variation in salinities (P<0.05). The overall taste panel score was highest at 9.5 + 0.5ppt. The possibility of the influence of salinity on flavor of cultured shrimps is suggested.